A closer look to the lower back and pelvis of the sporthorse
Back problems are difficult to diagnose and can be a cause of poor performance in (sport) horses. Kevin Haussler (chiropractor) examined the lower spine and pelvises of 36 Thoroughbred racehorses that died at the racetrack.
In literature is described that horses have 6 lumbar vertebrae (lower back) and five sacral vertebrae. However 39% of the horses in this study had either one less lumbar or one extra sacral segment. There was also a great variation in shape of the vertebrae. In 28% of the horses Haussler found complete fusion or bony bridging of the vertebrae joints. It was found that bone growth stops at the age between 3 and 5 years of age.
In 94% of the horses an asymmetry of the tuber sacral was found, often referred to as “hunter’s bump”. This is associated with pelvic fractures or ligament injury. However, these horses showed no signs of ligament injury, only variations in bone symmetry (conformation). Arthritic changes were found in all spines at different locations.
Stress fractures were found in 28% of the spines and in 25% of the pelvises, located close to the SI-joint. This can be due to; imbalance between spinal and pelvic muscle forces, an injury to the lumbar spine musculature or trauma.
Diagnostic techniques as ultrasound and scintigraphy (bone scans) are being used to visualize this type of problems.
> From: Haussler, JeVS 16 (1996) 279 - 281. All rights reserved to Elsevier B.V.. Click here for the online summary.